feat: dashboard 3-column layout — project folders treeview, project cards with open button, info panel

backend/src/database/schema.sql

@@ -99,6 +99,25 @@ CREATE TABLE IF NOT EXISTS settings (
   updated_at TEXT NOT NULL DEFAULT (datetime('now'))
 );
 
+-- ─── Project Folders ───────────────────────────────────
+CREATE TABLE IF NOT EXISTS project_folders (
+  id TEXT PRIMARY KEY,
+  name TEXT NOT NULL,
+  parent_id TEXT,
+  owner_id TEXT NOT NULL,
+  created_at TEXT DEFAULT (datetime('now')),
+  FOREIGN KEY (parent_id) REFERENCES project_folders(id) ON DELETE CASCADE,
+  FOREIGN KEY (owner_id) REFERENCES users(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_project_folders_parent ON project_folders(parent_id);
+CREATE INDEX IF NOT EXISTS idx_project_folders_owner ON project_folders(owner_id);
+
+-- ─── Projects: add folder_id column ─────────────────────
+-- NOTE: ALTER TABLE is idempotent-safe via try/catch in adapter; schema.sql
+-- is only exec'd on fresh databases. For existing DBs, the adapter runs
+-- the ALTER in init().
+
 -- ─── Indexes ────────────────────────────────────────
 CREATE INDEX IF NOT EXISTS idx_drawings_project ON drawings(project_id);
 CREATE INDEX IF NOT EXISTS idx_layers_drawing ON layers(drawing_id);